A LANDSLIDE RISK ASSESSMENT PROJECT FOR THE MOUNTAIN STATE OF WEST VIRGINIA

The West Virginia GIS Technical Center began a statewide landslide investigation in June 2018, as part of a FEMA-supported multi-hazard risk assessment project. Long-term goals include creation of county-level landslide susceptibility maps, interactive web map applications for displaying and collecting landslide information, and development of state and local landslide risk reports to better inform emergency preparedness and hazard mitigation planning. Initial stages have included creating a digital statewide landslide inventory, mapping over 76,000 previously identified slope failures, and compiling a West Virginia landslide bibliography. Other preliminary statewide products include generalized maps of bedrock lithologic resistance and dominant soil parent materials. A detailed map of slope elevation change and a statewide slopeshade have been created from the best available bare earth DEMs, and will be modified as FEMA QL2 LiDAR coverage is completed in West Virginia over the next 24 months. Landslide incidence modelling will be based on various inputs, such as geology, soils, topography, proximity to transportation infrastructure, and flow-accumulation generated stream networks.

Observations confirm the USGS Professional Paper 1183 Landslide Overview Map portrayal of West Virginia as a state in which landslide incidence is nearly ubiquitous. However, regional variations in slope failure types are pronounced. Debris slumps, debris slides, rock falls, and short-runout debris flows, appear to dominate in nearly flat-lying-bedrock terrain typical of western portions of the state, whereas long-runout debris flows and huge planar rock slides add to the landslide population in folded-bedrock landscapes of eastern West Virginia. Quaternary river rerouting and valley incision, Pleistocene periglacial instability, and anthropogenic activities play key roles in regional slope stability. NRCS Major Land Resource Areas demarcate regional landscape variation more accurately than provinces shown on existing physiographic maps, and may be useful in focusing regional training initiatives and communicating landslide incidence and risk at regional, county, and watershed levels.